Techniques have long been known for measuring the rate of movement of components in diverse forms of equipment and in various industries. For example, optical techniques for measuring the speed of rotation, of rotating components (such as turntables of phonographic equipment, and rotating parts of automotive engines and other rotary machinery) are well established. Also, translational or linear motion of component can be measured using various gauges and sensor elements or switches. Further, it is known to use optical devices to obtain data indicative of position from a computer mouse.
Difficulties arise when it is desirable to measure with great precision the (possibly relatively slow) rate of linear, axial motion of an elongate article, especially if the article is a relatively delicate or fragile cable or rod. Such problems arise, for example, when it is the rate of movement of a medical implement, or the cable to which it is attached, that is to be accurately monitored/controlled.
The present seeks to overcome the aforementioned problems and provide an improved motion rate sensor.